Eraser



April 1941- G. F. MILLER 2,239,793

ERASER Filed Dec. 30, 1938 M1 imlmmltmmm Patented Apr. 29, 1941 ET ED STAT ES i -T EN G'F'F 1 6E 8 Claims.

The invention relates to improvements in erasers in which a body of abrasive material is used to remove mechanically ink, graphite, and other substances from paper and other materials; and the objects of the improvement are, first, to provide a detachable handle for a body of abrasive material; second, to control, in the detachable handle, the rotation of a body of abrasive material about its own axis; third, to provide for the automatic adjustment of a body of abrasive material ,to the handle as that body wears; and fourth, to provide a-means for pressin a body of abrasive material firmly between lateral supports and forholding said body of abrasive material between said lateral supports.

One form of the invention is illustrated in the accompanying drawing in which Figure 1 representsin perspective the entire eraser in the assembled condition; Figure 2 represents a section of the entire eraser; also in assembled condition, at a right angle to the broader side shown in Figure 1 and along the lines 2 2 of Figure 1; Figure 3 represents the three principal parts of the eraser in an unassembled condition; Figure 4 is a section which represents the details of said body of abrasive material, and the supports on each side of said body of abrasive material; and Figure 5' is a section which represents the detailsiof'oneof the members of the pair of said lateral supports.

The body of abrasive material I is in one continuous part (a discoidin the present instance). The central area H and I6 of said abrasive discoid (see Figures 3 and 4) is cylindrical in shape and raisedabove the surf-ace of the surrounding area 8.: This central area on each side of the abrasive discoid is divided into an annular rib l5 and a cylindrical trunnion or axle II. The trunnion extends beyond or higher than the rib and between the trunnion H and the rib l6 and. separating the same is an annular groove 9 which is engaged by the inner one of two connective metal ribs provided on the face of the metal disk 2. This metal disk is the lateral support constituting the end of the resilient shank.

Two resilient shanks, curved toward each other in their open condition (see Figure 3), 4 4 are continuous with and terminate in two supports (disks in the present instance). The shanks 4 4 are continuous with and connected by the resilient loop l3.

Each annular rib It or" the abrasive discoid is radially symmetrical, uniform in height and width at every point, and each is a duplicate of the other Each of these two ribs bears between Lil the two concentric metal ribs on each side of the adjacent surfaces of the disk supports 2 2. The two cylindrical mandrels or axles H H are bilaterally symmetrical and identical the one with the other in shape and size. Each trunnion or axle is adapted to and bears in one of the circular openings It) It] (see Figures 4 and 5).

In handle 5 is a slot 7 (see Figures 1, 2, and 3), rectangular in the present instance, formed by the removal of a part of the material within and of the handle. Thus the walls of the slot are formed by and constitute a part of the body of the handle. One purpose of the walls surrounding the said slot is to force the pair of resilient shanks 4 toward each other and into contact with the abrasive discoid. The said walls also are an essential factor in causing, in combination with the resilient loop l3, the friction which prevents the pair of shanks 4 from moving in respect to the handleand the abrasive discoid 8 while erasure is taking place.

The three principal parts of the eraser (see Figure 3) are assembled as follows: The abrasive discoid I is inserted between the disks 2 2. The rounded end of the loop I3 is inserted into the opening la (see Figure 1). Then loop I3 and parts of shanks 4 4 are pressed into and through opening la and into the slot 'lof handle 5. That operation brings the shanks 4 4 parallel to each other and as closely together as is the thickness of the outer area 8 of discoid I. Also by that operation disks 2 2 are brought closer to each other, and each annular'rib I6 of the abrasive discoid passes in between the two concentric metal ribs which are on adjacent sides of the pair of metal disk supports, (see Figure 5) The resilient pressure upon the curved shanks in the opening Ia holds the ribs andthe trunnions or axles in the circular openings and. also prevents the said shanks from moving in-respect to the handle while erasure is taking place. The pressing of curved shanks 44 into opening la (rectangular in the present instance) also brings the edge or rim of the abrasive discoid l into contact with handle 5 at opening 1a This contact of said discoid with handle 5 prevents the discoid from automatically rotating. Whenever such rotation is desired, the abrasive discoid I is moved out of contact with the handle 5 without the position of the abrasive discoid, relative to the other parts in contact with it, being thereby changed. Abrasive discoid I may be released and removed from disks 2 2 by moving the handle 5 relative to shanks 4 4 until the point where said shanks in assembled condition come into contact with each other i8 is in the opening la. Disks 2 2 then spring apart automatically and annular ribs l6 I6 and cylindrical trunnions or axles H II are automatically disengaged from between the annular metal ribs on the face of each disk support and from within the circular space formed by the inner annular ribs of the pair of disk supports, respectively. Pin 6, forming no part of the present invention, between the sides of loop I 3 prevents the loop from moving out through opening la and separating from handle 5.

As the rim of the abrasive discoid I wears to a smaller circumference, loop 13 moves, because of the normal pressure on handle 5 while erasures are being made, farther up in opening 1 and carries shanks 4 4, disks 2 2, and abrasive discoid l farther toward said handle until the edge or rim of abrasive discoid l comes into contact with handle 5 at opening la. Thus the automatic adjustment of the arbrasive discoid to the handle whenever said discoid wears to smaller circumferences is provided for.

I am aware that prior to my invention the placin of bodies of abrasive materials between resilient shanks and holding such bodies of materials in place by forcing the shanks into a slot was practiced. I therefore do'not claim such a combination broadly; but I claim:

1. The combination in an eraser of a discoid body of abrasive material, a cylindrical trunnion projecting axially from each side of said body,

a pair of annular ribs, one surrounding each cylindrical trunnion, both annular ribs and trunnions continuous with and parts of said body of abrasive material and a pair of curved resilient shanks terminating in a pair of disks having concentric grooves and central perforations to re ceive said ribs and trunnions respectively.

2. The combination in an eraser of a discoid body of abrasive material, a cylindrical trunnion projecting axially from each side of said body and the said body having a pair of annular grooves, one surrounding each cylindrical trunnion, both cylindrical trunnions continuous with and part of said body of abrasive material, and a pair of curved resilient shanks terminating in a pair of disks, an annular concentric rib projecting from the side of each disk and received in the said annular grooves in the body aforesaid and the said disks having central perforations to receive said trunnions.

3. The combination in an eraser of a discoid body of abrasive material, a cylindrical trunnion projecting axially from each side of said body, a pair of annular ribs, one surrounding each cylindrical trunnion, both annular ribs and trunnions continuous with and parts of said body of abrasive material and the said body having a pair of annular grooves, one surrounding each cylindrical trunnion, and a pair of curved resilient shanks terminating in a pair of disks having concentric grooves and central perforations to receive said ribs and trunnions respectively and an annular concentric rib projecting from the side of each disk to be received in the said annu- Iar grooves in the body aforesaid.

4. The combination in an eraser of a body of abrasive material, an annular rib projecting from the side of the said body and continuous with and a part of the said body, a pair of shanks, one of the said shanks having means for engaging the said annular rib so as to secure the said body between the said shanks and in such a manner as to provide a friction surface with the said annular rib.

5. The combination in an eraser of a body of abrasive material, a cylindrical trunnion projecting axially from the side of said body and continuous with and a part of the said body, a pair of shanks, one of the said'shanks having means for engaging the said trunnion so as to secure the said body between the said shanks.

6. The combination in an eraser of a body of abrasive material having an annular groove formed in the side of the said body, a pair of shanks, an annular concentric rib projecting from the side of one of the said shanks and positioned in the said annular groove in the body aforesaid in such a manner as to secure the said body between the said shanks and provide a friction surface with the said body.

'7. The combination in an eraser of a handle having a longitudinal slot therein with an opening at one end of the said handle, a pair of shanks slidably mounted in the said slot and adapted to releasably engage an eraser at the termini thereof, each of the said shanks having a resilient longitudinal section and a curved portion positioned between the opposite ends thereof with the convex side of each curved portion of the said shanks positioned adjacent to the convex side of the curved portion of the other shank and the concave side of each curved portion of the shank aforesaid positioned opposite-the adjacent side of the slot aforesaid in such a manner that upon longitudinal adjustment of the said shanks so as to position the said curved portions adjacent to the opening to the said slot the said concave portions of the said shanks will engage the said handle at the opening to the said longitudinal slot whereby the said shanks will be positioned in' a disengagin relationship with the said eraser.

8. The combination in an eraser of a pair of shanks, one of the said shanks having a resilient longitudinal section and a curved portion positioned between the opposite ends thereof with the convex side of the said curved shank positioned adjacent to the other shank, a member slidably mounted on the said shanks adapted to engage the said shanks in such a manner as to hold the said shanks in engaging relationship with a body of abrasive material and the said member adapted upon longitudinal adjustment thereof to engage the concave side of the curved shank aforesaid in such a manner as to position the said shank in a disengaging relationship with the said body.

GEORGE F. MILLER. 

